Microbial Chemosensing as MIC Driving Force

Basing on extensive scanning electron microscopy and energy dispersive X-ray analyses on aeronautical aluminium alloys a new microbial influenced corrosion mechanism was demonstrated. The first evidence of the fungus Hormoconis resinae chemosensing capacity as the MIC driving force was published in 1990. Electrochemical results obtained since the seventies in aqueous cultures as well as in drained water from contaminated aircraft fuel tanks were interpreted as the addition of various corrosion processes. The supposed at random or stochastic microbial colonization of alloy surfaces, as suggested certain authors during these studies, was clarified when microscopic observation coupled to EDAX revealed a direct correlation between colonization sites with determined phases or inclusions on different alloy samples. However, the revealing main factor, associated to the always localized attack on secondary phases of the alloys was demonstrated well afterwards, when the “drop test” was added to these corrosion studies. Updated information was since revealed providing a different approach to the problem through scanning electron microscopy and energy dispersive X-ray analyses. The apparent MIC random attack distribution was caused by the secondary phase localization through the alloys during their solidification and not by the further microbial colonization of the respective site.